Blends and copolymers of polymerized acetylene and method of molding same



United States Patent BLENDS AND COPOLYMERS OF POLYMERIZED ACETYLENE AND METHOD OF MOLDING Patented June 10, 1958 have a lower tensile strength and are less rubbery than pure polybutadiene. They maybe easily shredded to the desired size and shape for injectionmoldin g. The flow, for example, of a 1:1 ratio blend of the two polymers SAME 6 before molding was M (medium on the thermoplastic scale). i? Buselh, New Piovldence P Tobolsky The polymer blends of polyacetylene and polybutadirmceton, N. J., asslgnors to Air Reduction Company, f 31 b Incorporated, New York, N. Y., a corporation of New ene m varymg raflos o or y welght York may be molded at low pressures, say, from 500 to 9000 10 p. s. i., and at temperatures ranging from 200C. to 300 N0 Drawillg- {\pplicatioll March 1953 C. to produce molded pieces that are well knit, smooth Sel'lal N0- and sharp edges 14 Claims (CL Chlorinated polyacetylene containing any desired.

amount of chlorine, for example from 0% to 40%, and This invention relates to polymer blends and has for 15 polybutadiene in suitable proportions may be compresits object the provision of blended products comprising sion molded at 250 C. in less time than the non-chloripolyacetylene, sometimes called cuprene or carbene, and nated polyacetylene. For example, a polymer contain? polybutadiene-containing elastomers and molded articles ing 14% chlorine maybe compression molded at 250' made from the blends. The invention not only covers C. in thirty (30) minutes or almost instantly at 300 C.; blends formed of polyacetylene but blends formed of however, i some Cracking y pchlorinated polyacetylene. The blended products of the Polyacetylene andchlorinated polyacetylene appear to invention comprise polyacetylene and polybutadiene or be reactive fillers for unsaturated elastomers and resins G.. R. S. rubber (a copolymer of butadiene and styrene) that are stable to high temperature compression and in blended in any suitable mechanical kneadingor working jection molding operations without exercising any maoperation. The polymer blends can be molded to give terial adverse effect. The molded pieces showed no tendsolid objects having good physical, machining, chemical, ency to deform at temperatures up to 300 C. and showed and electrical properties. The highly cross-linked moldlittle cold flow. Both impact strength and hardness are ed articles show no softening point and have excellent subject to conditions of molding. resistance to oxidative degradation, even at elevated tem- Blends of G. R. S. rubber and polyacetylene in varying peratures. proportions by weight, for example, from 25% to 75% The two polymers are incompatible and must be of polyacetylene, have similar properties but the curing broken down in a milling operation, the polyacetylene process is faster and requires lower temperatures than serving as a reactive filler. The polymer blends may be blends of polybutadiene and polyacetylene. Effective formed by milling the components thereof in mechanical molding temperatures of polyacetylene and G. R. S. kneading, smearing or sheeting operations of the type rubber range from 200 C. to 250 C. s commonly used in blending rubber and other plastics The molded articles of the polymer blends of the inand the blended product or stock maybe cut into any vention may be cured outside the mold after first pr'e suitable shape as strips, ribbons, or shreds to facilitate forming at moderate temperatures. It appears to beadtheir use, as in molding. These operations are advanvantageous to subject the articles, especially polybutaditageously carriedout at temperatures varying from 100 40 ene blends, to a preforming stage at a temperature of to 120 C. and temperatures within this range do not around 200 C. The molded articles may be held in appear to affect the moldability of the blends. Polymer the mold during the entire curing period or they may blends of polybutadiene-containing elastomers may be be removed from the mold and placed in a curing oven prepared in various proportions by weight, varying, say, or chamber. from 25 to 75% of polyacetylene or chlorinated poly- The following table illustrates the conditions of mold acetylene. The polymer blends may be molded in ordiing two-inch diameter discs of polyacetylene and poly. nary molds or injection molded under pressure and at butadiene, chlorinated polyacetylene and polybutadiene, elevated temperatures, preferably below 300 C. and polyacetylene and G. R. S. rubber, and describes cer- Polybutadiene-polyacetylene blends before molding tainproperties of the molded discs:

Table I No. Substance Temp., Pressure, Time, 'Results "0. p. s.l. Minutes {28%; gii zgiif fjl"""j 300 5,000 0 Hard disc, high rebound elasticity. 2 --{2aalaaaa.- so a ggggff fif f 300 a, 000 00 Hard disc, cracked. 4 zgg gff gg g t 300 2,000 15 Somewhat rubbery. 5 "i283; i fidtti gltgg 800 2,000 30 Solid hard disc. 0 ggg%$ 6 300 2,000 Hard disc but cracked. 7 zggigfi fifg 300 2,000 30 Hard disc, good rebound elasticity.

8i%$;tgl

300 2,000 0 Somewhat rubbery. 9 i833 5300502335,; :1} 300 2,000 00 Hard disc, not cracked.

50% Chlorinated (14% Ol 10 olyacetylene. 250 5,000 30 Hard solid disc obtained.

50 a Polybutadiene {60% Ohlorlpated (14% 01) 1 300 5 m0 0 v h da s b n u 50$3iiah$hibne i iiiim: co m Table I-Continucd No. Substance Temp, Pressure, Time, Results O. p. s. i. Minutes 39% Polybutadiene 12 267 Carbon Black- 300 5,000 30 Very hard disc obtained, negligible j 35? golyacegylenecold flow characteristics.

50 o yace y one. 13"--- 3 polfibumdigm g 210 6,000 o Gooadydisc formed, but soft and rub to en. 14 50% polyacetylene 2.10 5,000 Hard slightly flexible disc formed. 15 50% rubber 300 3,000 30 Very hard disc obtained. Appeared 8g g fi g gg very brittle.

ru er 1e {35 g gi s ai g 230 s, 000 30 Hard disc obtained.

ru er l7 2 g; 210 a, 000 Good disc obtained, slightly rubbery. 5 o o yace y ene. 1s Polybumdiene 300 1,000 0 H3113 felts; excellent rebound 1 Maximum temperature reached during heating.

For example, articles molded of blends of 50% polyacctylene and 50% polybutadiene at 300 C. and 3000 p. s. i. have dissipation factors measured at l mo. of from 0.005 to 0.04 and dielectric constants of from 2.5 to 3.0 depending on the time of heating in the mold, say, from 15 minutes to 45 minutes. By way of comparison, gcncral purpose Bakelite and hard rubber have dielectric constants of 7.0 and 2.8 respectively.

The highly cross-linked polymers showed very little cold flow properties. Some specimens, for example, specimen 12 of Table I, had better cold fiow properties than nylonfiber glass laminates.

The thermal stability of 1:1 (by weight) polyacetylenepolybutadiene molded discs at 700 C. in an inert atmosphere of purified nitrogen is about the same as polyacctylene; however, the article may lose as much as 25 of its original weight. Moreover, articles heated to such temperatures will probably undergo considerable crackmg.

The impact resistances of molded polyacetylene-polybutadiene blends were determined according to A. S. T. M. Standards D256-47T, Izod type, and the hardness by Standard D785-48T, except that the specimens were not conditioned. Specimens varying from 25% to 50% polyacetylene by weight with the balance polybutadiene, had impact resistances in foot pounds per inch of notch of from 0.23 to 0.44 and Rockwell hardness of M73 to M88. The impact strength and hardness of these molded polymer blends are generally better than the phcnolics and polyacctylenc. The mechanical properties of the polymer blends are very desirable and not only compare favorably in many respects to the properties of general purpose Bakelite and hard rubber but in some respects are superior.

The following table shows the Rockwell hardness of several specimens of polyacetylene-polybutadienc blends:

Table II Molding Conditions Rockwell Composition Hardness Temp, Pressure, Time,

C. p. s. i. Min.

50% Polyncetylene 300 6, 000 30 M 103 D0 300 9, 000 15 IVI 300 9,000 15 1\I 300 7,000 15 lvl 85 300 5, 000 15 M 113 Do 300 5,000 0 M 101 65 0 Poiyacetylend. 300 1, 000 0 M 30 From Table II it appears that the higher the conccntra tion of polyacetylene, the more rapid the cure.

ride, two of the best solvents for non-cross-linkcd polybutadiene were used. The samples were weighed before and after immersion in solvent.

The following table illustrates the solvent swell of polybutadicnc-containing blends:

is placed in a steel bomb containing oxygen at p. s. i. and the temperature is increased slowly, a sharp rise in temperature and pressure occurs between ll5150 C.; this temperature is the oxygen stability temperature. Sincc saturated polymers such as polyethylene have greater oxygen stability, approximately 210 C., it appears that the low oxygen stability is due to the residual unsaturation in polybutadiene and polyacctylene. The oxygen stability of highly cross-linked polybutadiene and the 1:1 polyacetylenc blend are very similar, being in the range of 360-370 C. Only when a large excess of polyacetylcne is present, such as the 1.2 weight ratio, does the oxygen stability show a marked drop. It appears then, that not only is the oxygen reactivity of polybutadiene greatly decreased but also that of polyacetylene. These facts are in agreement with the present belief that polyacetylene behaves as a reactive filler and that during the curing cycle a true chemical reaction is occurring. The low values of solvent adsorption in Table III also tend to indicate this fact. Solvent swell of the last test of Table III as measured by linear dimensional change is approximately 15% after 24 hours immersion. Polybutadiene baked alone at 255 C. for 3 days showed a solvent swell of approximately 20%. This also is in agreement with the probability that polyacetylene acts as a reactive filler when the polymer blends are molded at high temperatures.

We claim:

1. A polymer blend comprising cuprene and a synthetic elastomer selected from the group consisting of polybutadiene and a copolymer of butadicne and sytrenc.

2. A molded article formed by molding under pressure and at an elevated temperature a polymer blend comprising cuprene and a synthetic elastomcr selected In determining the solvent swell properties, 2-inch discs were immersed in a suitable solvent until solvent solute equilibrium was reached. Benzene and carbon tetrachlofrom the group consisting of polybutadiene and a copolyme; of butadieuc and styrene.

3. A polymer blend comprising chlorinated cuprcne and a synthetic elastomer selected from the group consisting of polybutadiene and a copolymer of butadiene and styrene.

' 4. A molded article formed by molding under pressure and at an elevated temperature a polymer blend comprising chlorinated cuprene and a synthetic elastomer selected from the group consisting of polybutadiene and a copolymer of butadiene and styrene.

5. A polymer blend comprising cuprene and polybutadiene in the range of ratios by weight of from 1:3 to 3:1.

6. A polymer blend comprising cuprene and a copolymer of butadiene and styrene in the range of ratios by weight of from 1:3 to 3:1.

7. The method of forming molded articles which com prises blending cuprene and polybutadiene, and molding articles of the polymer blends at a temperature of at least 200 C. and at a pressure of at least 500 p. s. i.

8. The method of forming molded articles which comprises blending cuprene and a copolymer of butadiene and styrene, and molding articles of the polymer blends at a temperature of at least 200 C. and at a pressure of at least 500 p. s. i.

9. The method of forming molded articles which comprises blending chlorinated cuprene and polybutadiene, and molding articles of the polymer blends at a temperature of at least 200 C. and at a pressure of at least 500 10. The method of forming molded articles which comprises blending chlorinated cuprene and a copolymer of butadiene and styrene, and molding articles of the polymer blends at a temperature of at least 200 C. and at apressure of at least 500 p. s. i.

11. A polymer blend comprising a cuprene selected from the group consisting of cuprene and a chlorinated cuprene and a synthetic elastomer selected from the group consisting of polybutadiene and a copolymer of butadiene and sytrene.

6 12. A molded article formedby molding under pressure and at an elevated temperature a polymer blend comprising a cuprene selected firom the group consisting of cuprene and a chlorinated cuprene and a synthetic 5 elastomer selected from the group consisting of polybutadiene and a copolymer of butadiene and styrene.

13. A polymer blend comprising a cuprene selected from the group consisting of cuprene and chlorinated cuprene and a synthetic elastomer selected from the group consisting of polybutadiene and a copolymer of buta (liens and styrene in the range of ratios by Weight of said cuprene to said synthetic elastomer of from 1:3 to 3:1.

14. The method of forming molded articles which comprises blending a cuprene selected from the group consisting of cuprene and chlorinated cuprene and a synthetic elastomer selected from the group consisting of polybutadiene and a copolymer of butadiene and styrene, and molding articles of the polymer blends at a temperature of at least 200 C. and at a pressure of at least 500 20 p. s. i.

References Cited in the file of this patent UNITED STATES PATENTS 25 1,522,822 Kuhn Jan. 13, 1925 2,213,423 Wiezevich Sept. 3, 1940 FOREIGN PATENTS 667,863 Germany Nov. 22, 1938 OTHER REFERENCES The GR-S Manual, page 38, published by Imperial Chemical Industries, Ltd., Dyestufis Division, 1947.- 

1. A POLYMER BLEND COMPRISING CUPRENE AND A SYNTHETIC ELASTOMER SELECTED FROM THE GROUP CONSISTING OF POLYBUTADIENE AND A COPOLYMER OF BUTADIENE AND SYTRENE. 